Qianli Chu

Synthesis of fluorinated pyrazole derivatives from β-alkoxyvinyl trifluoroketones

Abstract 1,1,1-Trifluoro-4-ethoxy-3-butene-2-one, 3-trifluoroacetyl-3, 4-dihydro-2H-pyran or furan reacted readily with pentafluorophenylhydrazine or per(poly)fluoroacectylhydrazine R f CONHNH 2 (R f : BrCF 2 , C 3 F 7 ) to give N -substituted-5-hydroxy-5-trifluoromethyl heterocycles Y  N  N  CH  CH ( R ) C ( OH ) CF 3 (Y: H, Ar f or R f CO), which were dehydrated by treatment with P 2 O 5 or SOCl 2 to form N -substituted 5-trifluoromethyl pyrazoles Y  N  N  CH  C ( R ) C CF 3 (Y: H, Ar f or R f CO) in good yields. Download full-size image

A convenient preparation of octafluoro[2,2]paracyclophane and dodecafluoro[2,2]paracyclophane

Abstract A new and convenient synthesis of octafluoro[2,2]paracyclophane and dodeca-fluoro[2,2]paracyclophane is reported. It is accomplished by treatment of 1,4-bis(halodifluoromethyl)benzene with PbBr2/Al in DMF at room temperature via the cyclocoupling of the reactive intermediate α,α,α′α′-tetrafluoro-p-xylylene.

Study of the reactions of fluorinated α,β-unsaturated carbonyl compounds with nitrogen and sulfur dinucleophiles

Abstract The fluorinated α,β-unsaturated ketone 1,1,1-trifluoro-4-ethoxy-3-butene-2-one reacted with dinucleophiles such as 2-aminothiophenol and 2-amino-ethanethiol to give trifluoroacetyl substituted 4H-1,4-benzothiazine, or 4H-1,4-thiazine, while the reaction of 5-trifluoroacetyl-3,4-dihydro-2H-pyran or 4-trifluoroacetyl-2,3-dihydro-furan with 2-amino-phenthiol gave 3-(2,2,3-2H-benzothiazolyl)-2-(trifluoromethyl)- tetrahydrofuran-2-ol or 3-(2-2,3-2H-benzothiazolyl)-2-(trifluoromethyl)- tetrahydro-2H-pyran-2-ol, respectively.

Synthesis of fluorine-containing symmetrical N,N-alkylidene bisamides

Abstract Fluorine-containing N , N -alkylidene bisamides RCH(NHCOR f ) 2 (R: H, Aryl; R f : CF 3 , CF 2 Cl, 2,6-C 6 H 3 F 2 ) are conveniently prepared in good yields by the reaction of corresponding aldehydes with fluorine-containing amides (R f CONH 2 ) in the presence of fluoroalkanesulfonic acids R f ′SO 3 H(R f ′: CF 3 , HCF 2 CF 2 , ICF 2 CF 2 OCF 2 CF 2 ).

A Novel Method for Preparation of Trifluoromethyl Substituted 2,3-dihydro-1,4- diazepine and Benzimidazole

Abstract Ethylenediamine reacted readily with 4-ethoxy-1,1,1-trifluoro-3-butene-2-one to form 5-trifluoromethyl-2,3-dihydro-1,4-diazepine in good yield. Under the same reaction conditions o-phenylene diamine gave 2-trifluoromethyl benzimidazole and benzimidazole.

On the Nucleophilic Reactions of 5-Trifluoroacetyl-3,4-dihydro-2H-pyran

Summary. 5-Trifluoroacetyl-3,4-dihydro-2H-pyran react readily with many nucleophiles such as amines and Grignard reagents to give the rign opened products NuCH*CR1R2 (R1: (CH2)3OH, R2:CF3CO). The compound with Nu=Et2N is unstable; it rearranges to 1-hydroxyl-1-trifluoromethyl-2-diethylaminomethylene-tetrahydropyran and 2-diethylamino-3-trifluoroacetyl-tetrahydropyran via an intramolecular nucleophilic addition reaction. Hydrazine and hydroxylamine attack the carbonyl carbon of the title compound to form (CH2)3OCH*CC(CF3)*NZ(Z=NH2, OH). In the presence of KOH, however, hydroxylamine hydrochloride reacts additionally to 2-hydroxyl-2-trifluoromethyl-3-cyano-tetrahydropyran. Upon heating with triethylphosphite, the title compound reacts as a heterodiene and gives the corresponding cyclophosphorane. X-Ray diffraction analyses of two compound are presented.Zusammenfassung. 5-Trifluoracetyl-3,4-dihydro-2H-pyran reagiert bereitwillig mit vielen Nucleophilen wie Aminen oder Grignard-Verbindungen zu ringgeöffneten Produkten des Typs NuCH*CR1R2 (R1: (CH2)3OH, R2: CF3CO). Die Verbindung mit R=Et2N ist instabil und lagert über eine intramolekuare nukleophile Additionsreaktion zum 1-Hydroxy-1-trifluormethyl-2-tetrahydropyran um. Hydrazin und Hydroxylamin greifen das Carbonylkohlenstoffatom der Titelverbindung an und geben dabei Verbindungen des Typs (CH2)3OCH*CC(CF3)*NZ (Z=NH2, OH). In Gegenwart von KOH reagiert Hydroxylamin jedoch zusätzlich zu 2-Hydroxy-2-trifluormethyl-3-cyano-tetrahydropyran. Bei Erhitzen mit Triethylphosphit reagiert die Titelverbindung als Heterodien zum entsprechenden Cyclophosphoran. Die beiden Verbindungen wurden mittels Röntgenstrukturanalyse charakterisiert.

Reactions of 5-trifluoroacetyl-3,4dihydro-2H-pyran with zinc reagents

Abstract One pot reaction of 5-trifluoroacetyl-3,4-dihydro-2H-pyran with alkyl bromides Rbr in the presence of zinc powder gave the corresponding alcohol ( CH 2 ) 3 OCH=C C(R)(CF 3 )OH (R: CH 2 CO 2 Me, 3a ; CH 2 CHCH 2 - 3b ); 3a readily hydrolysed to the corresponding carboxylic acid under dilute acidic conditions, intramolecular cyclo addition of this acid afforded a bicyclo lactone.

A new route to 5-trifluoromethyl-2,3-dihydro-1,4-diazepine and 2-trifluoromethylbenzimidazole

Ethylenediamine reacted readily with 4-ethoxy-1,1,1-trifluoro-3-butene-2-one to form 5-trifliuoromethyl-2,3-dihydro-1,4-diazepine in good yield. Under the same reaction conditions, o-phenylenediamine gave 2-trifluoromethylbenzimidazole and benzimidazole.

SYNTHESIS OF DIETHYL N-(PERFLUOROALKANESULFONYL) PHOSPHORAMIDATES AND N-(PERF'LUOROALKANESULFONYL) PHOSPHORAMIDIC ACIDS

Abstract N-(perfluoroalkylsulfonyl)phosphoramidates are prepared by the reaction of diethylchloro phosphate CIP(O)(OEt)2 with sodium perfluoroalkylsulfonylamides RfSO2NHNa or sodium N-trimethylsilylperfluoroalkylsulfonylamides RfSO2N(Na)SiMe3 respectively. Hydrolysis of diethyl N-(perfluoroalkylsulfonyl) phosphoramidates under acidic condition did not give the expected RfSO2NHP(O)(OH)2 but led to a brake of the N-P bond forming the corresponding perfluoroalkylsulfonylamides. Silylation of RfSO2NEP(O)(OR)2 with Me3SiBr give high yields of RfSO2NHP(O)(OSiMe3)2 which were then treated with water at room temperature to afford the title phosphoramidic acids.

A convenient one-pot synthesis of per-(or poly-) fluoroalkanesulfonyl substituted cyclopropanes

Abstract Per-(or poly-) fluoroalkanesulfonyl substituted cyclopropanes are prepared by a facile one-pot reaction of methyl per-(or poly-) fluoroalkanesulfones with 1,2-dibromoethane under basic reaction conditions. Similarly treatment of benzyl per-(or poly-) fluoroalkanesulfones gave 1-phenyl-1-per-(or poly-) fluoroalkanesulfonyl cyclopropanes and trans -1,2-diphenylethene as the by-product which was formed by coupling of phenylcarbene.